Quickstart

This guide walks an onboarded partner through their first submission.

Prerequisites

A dedicated Capture endpoint URL (provided by nexroute during onboarding)
Source IPs allowlisted on that endpoint (coordinated during onboarding; see Authentication)

Methods

The endpoint speaks JSON-RPC 2.0 over HTTPS and WebSocket. Two submission methods are exposed:

eth_sendPrivateRawTransaction — submit a single user-signed transaction. Use this for the common case where the user signs one swap and you forward it as-is.
eth_sendBundle — submit an ordered list of user-signed transactions as an atomic bundle. Most useful when a swap needs its ERC-20 approval packed alongside it: pass [approval_tx, swap_tx] and the approval, swap, and backrun all land atomically. Mirrors Flashbots’ eth_sendBundle shape.

Any other method returns -32601 method not found.

Submit a single transaction

curl -X POST <YOUR_CAPTURE_ENDPOINT> \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_sendPrivateRawTransaction",
    "params": [{ "tx": "<RAW_SIGNED_TX>" }]
  }'

const response = await fetch('<YOUR_CAPTURE_ENDPOINT>', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_sendPrivateRawTransaction',
    params: [{ tx: '<RAW_SIGNED_TX>' }],
  }),
});

const data = await response.json();
console.log(data.result); // 0x... tx hash

Params is a single-element array containing an object with tx, the hex-encoded raw signed transaction (0x-prefixed). The object shape mirrors Flashbots’ eth_sendPrivateTransaction and reserves room for optional fields (e.g. maxBlockNumber) without further wire breaks. The signature is the user’s; nexroute does not modify the payload.

Response

The endpoint returns a JSON-RPC envelope echoing the request id. The result field contains the transaction hash (0x-prefixed, 32 bytes).

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x6b6f1c8f5d2c4a9d3e1f8b7c6a5d4e3f2c1b0a9d8e7f6a5b4c3d2e1f0a9b8c7d"
}

A non-error response confirms acceptance; nexroute is committed to delivery from this point. Use the hash to track inclusion in any block explorer.

Submit a bundle (approval + swap)

When the swap needs an ERC-20 approval the same user hasn’t issued yet, submit both transactions together so they land atomically with the backrun. Order matters: the last transaction is the source nexroute backruns behind; earlier transactions are dependencies bundled in front.

curl -X POST <YOUR_CAPTURE_ENDPOINT> \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "eth_sendBundle",
    "params": [
      {
        "txs": [
          "<RAW_SIGNED_APPROVAL_TX>",
          "<RAW_SIGNED_SWAP_TX>"
        ]
      }
    ]
  }'

const response = await fetch('<YOUR_CAPTURE_ENDPOINT>', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_sendBundle',
    params: [
      {
        txs: [
          '<RAW_SIGNED_APPROVAL_TX>',
          '<RAW_SIGNED_SWAP_TX>',
        ],
      },
    ],
  }),
});

const data = await response.json();
console.log(data.result); // 0x... bundle hash

The result field contains the bundle hash (keccak256 of the concatenated transaction hashes).

Errors

Errors follow standard JSON-RPC conventions:

Code	Cause
`-32601`	Method other than `eth_sendPrivateRawTransaction` or `eth_sendBundle`
`-32000`	Malformed transaction (RLP decode failure, invalid signature) or empty bundle
`-32603`	Internal error during forwarding (rare; nexroute always retries before surfacing)

A non-error response means the submission has been accepted into the routing pipeline. Subsequent inclusion is monitored automatically.

Next steps

Authentication: IP allowlist setup and operational notes
Security: what nexroute guarantees about your orderflow
eth_sendPrivateRawTransaction and eth_sendBundle: full method specifications

Getting started

RPC mode

Embedded mode

API reference

Prerequisites

Methods

Submit a single transaction

Response

Submit a bundle (approval + swap)

Errors

Next steps

​Prerequisites

​Methods

​Submit a single transaction

​Response

​Submit a bundle (approval + swap)

​Errors

​Next steps

Prerequisites

Methods

Submit a single transaction

Response

Submit a bundle (approval + swap)

Errors

Next steps